Characteristics of Karst Polje in Vietnam and Associated Geohazards

Karst is widely distributed in Vietnam, over area of ~60.000km2, which approximately accounts for 20% of the Vietnamese territory. Although there have been many studies on karst in Vietnam and around the world, only few of them focus on formation and development of karst poljes and well as its linkage to the geological hazards. The karst poljes in Vietnam are very important for socio-economic development. Recent researches show that formation and development of the karst poljes have occurred in stages. Most of the poljes have been constrained within fractured, faulted and folded Permo-Carboniferous limestone formations. The karstification process has led to not only formation of the karst poljes but also causing geological hazards such as flooding, sinkholes, and pollution of groundwater.